Well, I can't say much as of yet because I just joined Inkitt yesterday. However, there are a few promising things and some things you should beware of that I found out from my research. The good thing with Inkitt is you will keep the copyright of your story until you specifically sign a contract with them. (Like here on Tapas for example). Inkitt is rising in popularity because of it's wide variety of books in different genre. Another good thing is that readers can give you feedback/reviews directly after reading chapters of your story and rate different aspects of it with stars, etc. (They have a professional review form). To the audience itself and how fair they are I can't say anything yet because getting reads there proves to be just as difficult as on here (I got no reads so far but then again, I only have one chapter posted as of yet). Also, if you wish to delete your story, you can do that easily unless you enter a contest I think. So there's no need to worry in that department I think.
To the things you should be aware of, their interface looks good for readers but for writers it proves to be hell (my experience at least). Their website is really glitchy and it was a horror to try and upload the cover of my book (I had to google why it wasn't working and apparently it only works when you upload the cover with the inkitt writing app but that issue seems to be there for quite a while and it is still not fixed). For writing aka copy and paste the document as the manuscript, well, can't recommend that. They have an option to upload the word document directly onto the website and split it for chapters which is amazing and I would really recommend doing that and saving yourself a headache should you decide to post there.
Aside from this, the most important part you should know, if Inkitt ever offers you to publish your book/go into contract with them DO NOT accept the offer and sign the contract! That's where the big shady part comes in to. From what I read, they basically offer you a contract like any other (like Tapas etc), however, they give you only 20% cut of profit FOR A FULL BOOK YOU WROTE AND FOR YOUR ORIGINAL IDEA AND FOR A LICENSE TO YOUR COPYRIGHTS. Basically, they scam you with the contract. 20% is nowhere near enough to give you some good money from your book even if it does well while the 80% goes into their own pockets. For professional publishers and writers alike, this is a big red flag! You shouldn't even think about low-cutting yourself like that! The normal profit cut is 50-50, meaning you get 50% and your publisher gets 50% off all profits. (Sometimes more, sometimes less but this is the percentage I saw floating around. 20% is a joke for your hard work)
So, basically to sum it up, Inkitt is good to cross-post your stories or post your story/book there in general as long as you stay away from their shady contests and publishing contracts of any kind. As long as you are aware that if they are interested in putting you under contract, you have good chances to find a better publisher to publish your work with (or self publish) than their shady deals that rip you off. If it will gain much more popularity in the future is debateable, but if you want to have another platform to showcase your story/book/novel for free, Inkitt is okay to go to. Just stay away from the shady stuff and personally I wouldn't join their contests either because they are quite shady as well. Good luck and I am sorry I couldn't be of more help. 
Personally, I am chosing to give it a try but if I can't gain at least a few interested readers in two weeks, I will delete my story & account and move on from Inkitt.
